Carburetor having a pure fluid component



United States Patent 1111 3,547,414

[72] lnventor Giancarlo Nardi 56 References Ci d PISa UNITED STATES PATENTS {3. $55 gfg fl g 3,288,445 11/1966 Mennesson 261/50(.l)X

[4s] Patented M15197, 3,386,710 6/1968 York,Jr. 261/36(.l) 3,388,898 6/1968 Wyczalek 261/69X [73] Asb'gnee zfi wesmghouse 3,389,894 6/1968 Binder 26l/36(.l) Togrinoualy 3,477,699 11/1969 Drayer 26l/36(.1)

[32] Priority June 16,1969 PrimaryExaminer-Tim R. Miles [33] Italy Attorneys-Adelbert A. Steinmiller and Ralph W. Mclntire,

131 1 N0. 52248/69 Jr.

ABSTRACT: A carburetor having a fluidic proportioning device adapted to deliver fuel from a fuel tank to a fuel nozzle to inject fuel into an air intake conduit in proportion to air pressure differential between atmosphere and a venturi induced pressure in the air intake conduit impressed across the COMPONENT control inputs of the proportioning device, and including a 8 Chums 5 Drawmg Figs valve device mechanically coupled to an air flow responsive [52] U.S.Cl 261/36, throttle plate in the air intake conduit disposed upstream of l37/8l.5,261/50 the venturi area to proportionally modify the effect of the [51] F02m 7/04 pressure differential upon the proportional device in a [50] 26l/36.l, predetermined portion of the range of operation to increase 50.1; l37/81.5 efficiency ofoperation,

[54] CARBURETOR HAVING A PURE FLUID PATENTED nun 5mm 3547;414

SHEEI 1 IF 4 INVENTOR GIANCARLO NARDI ATTORNEY INVENTOR GIANCARLO NARD! ATTORNEY PATENTED DEL! 5197B PRESSURE DIFFERENTIAL IN mm H N (.1) O O sum 3 us 4 0 MIN I000 2000 3000 4000 5000 6000 ENGINE REVOLUTIONS PER MINUTE INVENTQR GIANCARLO NARDI ATTORNEY PATENTEU DEC! 5 I976 SHEET 4 0F 4 ENVENTOR GIANCARLO NARDI ATTORNEY CARBURETGR HAVING A PURE FLUID COMPONENT BACKGROUND OF INVENTION The prime purpose of a carburetion system is to mix a proportioned quantity of gasoline with air drawn in by the engine so as to assure a proper air to gasoline mixture for each rota tional speed and load condition of the engine. Present carburetion systems, especially those used in automobiles, and with the exception of a few complicated mechanical and electronic devices, achieve air to gasoline proportioning by direct injection of the gasoline into the engine in response to the vacuum which occurs in the air intake conduit of the engine. The vacuum condition is conventially increased by contouring the interior of the intake conduit in the formof the familiar venturi tube.

The above principle of operation of the conventional carburetor is fairly simple in theory but, in practice, it has been found impossible to achieve optimum air to gasoline mixture for each rotational speed and load condition of the engine, unless expensive and highly complicated correctiveapparatus is added to the carburetor device. Moreover, partial filling of the engine cylinders occurs at high engine speeds due to the narrower portion of the venturi-shaped air intake conduit and the locations of the jets or nozzles relative thereto.

In my Italian Pat. No. 824,478, filed'Feb. l6, I968, the above disadvantages of conventional carburetion systems were eliminated by providing an indirect injection carburetion system which did not directly utilize the airstreamin the intake conduit to draw fuel from the nozzle into the mixing area, but, instead, utilized a means sensitive to the pressure differential existing between the atmosphere and the air intake conduit of the engine for controlling gasoline under pump pressure, so as to proportion the quantity of fuel delivered to the fuel nozzle. The means so utilized was a pure fluid amplifier, having no moving parts, which delivered fuel from a fuel tank through a fuel pump to a fuel nozzle in the mixing area in proportion to the pressure differential across the control ports of the amplifier as provided by the pressure differential between a pair of feelers, one subjected to atmospheric pressure, and the other disposed in the venturi tube subjected to the lower air pressure produced by the air flow through the venturi tube. A spring-biased throttle valve or plate, disposed in the air intake conduit axially between the feelers provides an additional pressure differential for efficient operation of the amplifier at low engine speeds. By that construction, there was proposed a carburetion system very simple to manufacture, very quick to respond to acceleration, easy to enlarge to suit every type of internal combustion engine, and one which provides for the elimination of delicate devices such as the constant level float, the acceleration pump, adjustable nozzles, needle valves, diaphragms and bellows and interconnecting apparatus.

Although the aforementioned pure fluid as controlled by pressure differential between atmosphere and pressure within the venturi tube is effective to proportion delivery of fuel to the air intake conduit in accordance with various engine speeds and load conditions, the lower pressure within the venturi tube, as controlled by the venturi shape and air flow therethrough, is modified to some degree by the flow of air past the flow of air past the throttle valve or plate disposed in the air intake conduit axially between'the feelers to add a pressure differential to the venturi induced pressure differential to provide efficient operation of the proportional amplifier at low engine speeds, which throttle plate is spring biased to remain partially closed during engine startup and thereafter opens an amount proportional to the air flow through the air intake conduit. Accordingly, the air pressure in the air intake conduit is controlled simultaneously by the venturi .tube and the upstream throttle plate so that as theengine speed increases and the effect of the throttle plate gradually decreases the feelers in the venturi tube detect the venturi induced pres sure as modified by the presence of the throttle plate resulting in a pressure differential deviation preventing optimum air to gasoline mixture, particularly at the high engine speeds.

SUMMARY OF INVENTION Accordingly, it is the object of the present invention to provide, in a carburetor utilizing a pure fluid proportioning device to deliver fuel to a mixture chamber in proportion to the detected pressure differential between atmosphere and pressure in the engine air intake conduit, controlling the pure fluid device to compensate for the varying effect of an upstream throttle plate upon the air flow in the air intake conduit and to generally provide correction of the low pressure in the air intake conduit to provide a desired pressure differential across the fluid device for providing optimum proportioning of air to fuel mixture for all engine speeds and load conditions.

In the present invention, this object is achieved by adding to the control port circuitry of the fluidic proportioning device a compensatory control circuit capable of modifying the initial pressure difierential across the control ports as obtained from a pair of passages opening to the venturi tube, each control port connected to a different one of the opposing pair of con trol inputs of a fluidic proportional device. One passage is subjected to atmospheric or near atmospheric pressure while the will gradually close the valve device to reduce the effect of at I mospheric pressure on the air intake pressure condition detected by the aforementioned other passage opening in the air intake conduit downstream of the throttle plate, thus modifying the detected pressure differential to provide, for all engine speeds and load conditions, a compensation for the diminishing effect of the throttle plate as it opens in response to in- I creased air flow, to provide the proper pressure differential across the pure fluid device necessary to provide optimum air to gasoline mixture.

This and other objects will become more readily apparent in the following description, taken in conjunction with the drawing, in which:

FIG. 1 is a schematic representation of the carburetion system, showing my invention; 7

FIG. 2 is a sectional view of a portion of the carburetion system of FIG. 1, showing the details of the corrective valve device;

FIG. 3 is a graphical illustration of pressure differential con- I ditions across the pure fluid device relative to engine revolutions per minute;

FIG. 4 is a sectional view of the air intake conduit and cor- ,,rective valve device of FIG. 1, showing a modified arrangeiflment of components; and

FIG. 5 is a perspective view of the air intake conduit and corrective valve device of FIG. 4.

' Referring now to FIG. 1 of the drawing, there is disclosed a carburetion system including a pure fluid device 10 supplied 'iby a fuel reservoir 11 through a conventional fuel pump I2 connected to the reservoir by way of pipe 13 and connected to supply the pure fluid amplifier through a pipe 14 and an optional filter 15.

The pure fluid device 10 may comprise any conventional pure fluid device of the type known as a fluidic proportioning device, that is, a pure fluid device which operates to. deliver at one of two output ports an amount of supplied fluid proportional to the pressure differential across opposing control input ports. The fluidic device is biased, by structure or fluid pressure, to deliver all of the supplied fuel at the other of the two inputs when no pressure differential is present across the control ports Reference is made to my copending application (WABCO Case 6469) as illustrative of a basic internal structure in a proportioning device for providing all the supplied fluid at one of the two outputs in the absence of a pressure differential across the control ports.

The pure fluid device includes a supply port 16 connected to receive fluid under pressure from pipe 14, a first output port 17 communicated by apipe 18 to a spray nozzle 19 which injects fuel into the air intake conduit 20, and a second outlet port 21 communicated via pipe 22 to the aforementioned reservoir for returning to the reservoir that portion of the supplied fuel not delivered to the noule 19 via outlet 17 and pipe 18. Outlet port 21 is also communicated through an adjustable needle valve 23 and passageway 24 to the interior of the air intake conduit to deliver a predetermined quantity of fuel necessary to sustain the idling condition of the en gme.

The pure fluid device 10 further includes a pair of control ports 25 and 26 across which is to be provided a suitable pressure differential, in the manner hereinafter described in detail, for producing at outlet port 17, and nozzle 19 a proportional quantity of fuel necessary for perfect carburetion at each different engine speed.

Control port 26 is communicated by a pipe 27 and a choke 28 to a grove 29 disposed on the interior wall of the air intake conduit, the groove extending parallel to the air flow and having an openend intersecting a portion of the air flow to provide atmospheric or near atmospheric pressure to control port 26. Control port 25 is communicated by a pipe 30 and a choke 31 to the venturi-shaped interior of the air intake conduit 29 at the narrowest point 32, where, as a result of the well-known venturi effect, the pressure is lower than that at groove 29,

thus establishing across the pure fluid device 10 a pressure differential controlling the proportional amount of fuel delivered to nozzle 19 via output port 17 and pipe '18. Choke 31 establishes a biascondition for adjusting the gain of theproportioning device.

In order to provide an air-gasoline emulsion within nozzle 19 for bettering gasoline nebulization, a pipe 33 communicates groove 29 with the interior of the nozzle 19. I

The air intake conduit 20 is interiorly shaped in the familiar venturi tube configuration, and is provided with a pair of axially displaced throttle plates or valves 34 and 35, respectively. Throttle plate 35 is operated directly by the accelerator, not shown, in a conventional manner. Throttle valve or'plate 34 is disposed on an axially rotatable shaft 36 mounted in the wall of the air intake conduit 20, and is normally biased in a partially or fully closed condition, during engine starting, by a spring mechanism, hereinafter described in detail, and opens, after engine start, by an amount proportional to the air pressure on the plate as provided by the air flow in the air intake conduit. The throttle plate normally extends across the conduit to effect a larger pressure differential between passages 27 and 30, for low speedoperation of the engine, sufficient to exceed the initial threshold of operation of the proportioning device.

in accordance with the present invention, there is shown generally in FIG. 1 the corrective apparatus, generally indicated at 37, for directly modifying the lower pressure input to control port 25 through passage 30 to provide the optimum pressure differential across control ports 25 and 26 necessary to effect the desired proportioning of fuel to air mixture over the full range of engine speed and loading conditions.

The corrective apparatus 37 comprises a passage 38 communicating at one end with passage 30 at a point between choke 31 and control port 25, and opening at the other end to atmosphere by way of a valve device 39 disposed within a valve housing 40 and connected for operation by movement of the throttle plate 34.

Referring generally to FIG. 1 and more specifically to FIG. 2 of the drawing, it is seen that valve 39 is disposed for axial movement within housing 40, which may be integral with the air intake conduit, as shown, or may be detachably mounted thereon in any suitable manner. Valve 39 comprises a hollow spool member having its central portion externally necked at 41 and provided with one or more apertures 42 so that atmospheric pressure entering the housing 40 via an aperture 43 in the upper end thereof will be transmitted through the valve body and apertures 42 to a discharge port 44 disposed in the wall of the housing 40 in communication with aforementioned pipe 28.

in order to axially move valve 39 relative to discharge port 41 to gradually and proportionally open or close discharge port 41 in accordance with the pivotal position of upper throttle plate 34, there is provided a connecting rod 45 pivotally attached at one end to a transverse pin 46 extending through valve 39, the rod extending through aperture 43 and having the other end pivotallysattached to the end of .a lever 47 attached to shaft 36 supporting the throttle plate 34. A compression spring 48, disposed between one end of the valve member 39 and the inner end of the valve housing 40, serves the dual purpose of biasing the throttle plate 34 to the relatively closed condition forengine start, and, at the same time, disposes the necked portion 41. of spool valve member 39 immediatelyadjacent discharge port 44, as shown in FIG. 2 i I Referring now to FIG. 3 of thedrawing, thereis shown a plurality of curves comprising graphical illustrations of pressure differentials provided by-various'elements and combinations of elements of the above described apparatus over a given range of engine speeds, as follows: I

CURVE C1 pressuredifferential effected by the venturi shape of the air intake conduit without the intervention of any corrective apparatus; CURVE C2 pressure differential to be applied to thep'ure fluidde'vice 10 for achieving at output port 17 the fuel quantity necessary for perfect carburetion;

CURVE C3 pressure differential comprising curve C1 as modified by operation of the corrective apparatus 37; CURVE C4 pressure differential deviation of curve C3 if the spool valve 39 of the corrective apparatus 37 should not intervene,

in now describing the operation of the above-described apparatus, it will be assumed that the engine, not shown, has been started, and is in the idle condition or a speed condition slightly above idle, in which' eve nt 'pump 12 is supplying gasoline via pipes 13, 14 and filter 15 to supply port 16 of the pure fluid device 10. Under these conditions, a relatively low speed air flow through air intake conduit 20 impinges upon throttle plate 34 to partially open the throttle, to partially compress spring 48 and slightly raise spool valve 39 from the positionshown so that discharge port 44, remains fullyuncovered to permit atmospheric pressure within housing 40 and spool valve member 39 to pressurize passage 38 at full atmospheric pressure. The pressure differential established across control ports 26 and .25 comprises the difference between atmospheric pressure applied from groove 29 through choke 28 and pipe 27 to control port 26, and a lower pressure at control port 25- asprovided by atmospheric pressure in pipe 28 as reduced by both the venturi induced pressure at point 32 through choke 31 and pipe 30 and the relatively'closed condition of the throttle plate 34. The pressure differential so produced across the stream of fuel from supply port 16 to output port 21 provides a proportional flow of fuel to output 17 for delivery through pipe 18 to nozzle 19 for injection into the air intake conduit 20, the remainder of the fuel being delivered to output 2! for return to reservoir 11 via passage 22.

If the engine is operating at idling speed, the pressure differential established across control ports 25 and 26 is very low so that all or substantially all the fuel flowing through pure fluid device 10 is delivered at output 21 for return to the reservoir 11, a sufficient amount of fuel passing through choke 23 and pipe 24 to the air intake conduit to sustain the idle condition. 1

As throttle plate 35 opens and the speed of the engine increases, the air flow through the air intake conduitincreases, thus proportionally opening throttle plate 34, raising spool valve 39, increasing the pressure differential across control ports 26 and 25 as illustrated on curve C3 on the graph of FIG. 3 and proportionally delivering a larger quantity of fuel to nozzle 19.

It is to be noted that the proportional upward movement of the spool valve 39 does not begin to close discharge port 44 until there is achieved a pressure differential of P1 on curve C3 of the graph of FIG. 3, at which point it has previously been determined that, absent a correction of the pressure differential at engine speed above that point, the pressure differential across control ports 25 and 26, as illustrated by curve C4, is less than that necessary for perfect carburetion illustrated by curve C3, because as the throttle plate 34 opens further at increasing engine speeds, the pressure differential effected by its plate decreases.

Accordingly, by appropriate selection of linkage between throttle plate 34 and valve 39, the latter begins to close discharge port 44 at pressure differential point P1, and proportionally continues closing until fully closed at pressure differential point P2. By the proportionate closing of the discharge port 44, the pressure in pipe 38 is gradually reduced so as to have proportionally less effect upon the venturi induced low pressure in pipe 30 and control port 25, thus providing the higher pressure differential illustrated by curve C3 between the points P1 and P2, thereby producing a pressure differential curve substantially identical to the pressure differentials required for perfect carburetion as illustrated in curve C2.

FIGS. 4 and 5 of the drawing show a practical embodiment of the invention shown schematically in FIG. 1, comprising one means of conveniently arranging the pure fluid device ll) of FIG. I on the air intake conduit 20, corresponding parts being assigned the same reference numerals. The fluidic device comprises a flat plate having grooves, not shown, on the internal surface thereof, which grooves correspond to the internal passages of the fluidic device 10 of HO. 1, the ends of which grooves mate with corresponding. holes in the side of the air intake conduit, which holes correspond to the ends of the passages 19, 28 and 30 and others, not shown. The grooved plate structure is disclosed in my aforementioned copending application (WABCO Case 6469).

lclaim:

l. A carburetion system for internal combustion engines, comprising:

a. an air intake conduit;

b. a throttle valve in said air intake conduit;

c. means biasing said throttle valve to a relatively closed condition and yieldable to open said throttle valve an amount proportional to the magnitude of the air flow in said air intake conduit;

d. a fuel nozzle opening to the interior of said air intake conduit;

e. a pure fluid proportional amplifier having a supply port for receiving fuel under pressure, a pair of output ports, and a pair of control pressure input ports;

f. a first passage communicating one of said output ports to k. means for opening and closing said fourth passage relative to atmosphere; and

1. means connecting said valve means to said throttle valve for closing said valve an amount proportional to the amount said throttle valve isopen from the relatively closed position. 2. A carburetion system for internal combustion engines, as

recited in claim 1, in which;

a. said air intake conduit includes an internally narrowed portion intermediate its ends and downstream of said throttle plate forming a venturi tube; and b. said third passage communicating with said air conduit at said narrowed portion.

intake 3. a carburetion system for internal combustion engines, as

recited in claim 1, further including:

a. a fuel reservoir;

b. means including a pump for supplying fuel under pressure to said supply port; and 1 c. a fuel return passage communicating the other of said pair of output ports to said reservoir. 4. A carburetion system for internal combustion engines, as recited in claim 3, further including, a fifth passage communicating said fuel return passage to the interior of said air conduit.

5. A carburetion system for internal combustion engines, as

recited in claim 4, in which, a variable choke is disposed in said fifth passage. 7

6. A carburetion system for internal combustion engines, as recited in claim 1, in which a choke is disposed in one of said second and third fluid passages for biasing the pure fluid proportional amplifier.

7. A carburetion system for internal combustion engines, as I recited in claim 1, in which a sixth passage communicates the interior of said air intake conduit upstream of said throttle valve with the nozzle to produce an emulsion of air and fuel before injection by the nozzle into the air intake conduit.

8. A carburetion system for internal combustion engines, as recited in claim 4, further including:

a. an accelerator throttle valve disposed in said air intake conduit; and b. said fifth passage communicating with the interior of said air intake conduit downstream of said throttle valve. 

